New 1,7-Disubstituted Perylenediimides as Molecular Acceptors for Organic Solar Cells

Two perylenediimides (PDIs), PT and PT2, functionalized with thiophene heterocycles on the 1,7-positions of the bay region were synthesized and utilized in inverted bulk-heterojunction (BHJ) polymer solar cells as acceptors in the photoactive layer. The synthesized PDIs were thermally stable up to 453°C and soluble in chlorinated solvents such as dichloromethane and chloroform. PT or PT2 was blended with poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]bithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PCE-10) as a donor material. The inverted BHJ solar cell fabricated using the PCE-10:PT photoactive layer showed the highest power conversion efficiency (PCE) of 2.06%. Film morphology studies of PCE-10:PDI blends revealed a relationship between the film nanostructure and device performance.